Centrifugal clutch control



Sept. 12, 1950 A. PITT CENTRIFUGAL CLUTCH CONTROL Filed Aug. 25, 1945 INVENTOR. ARNOLD PITT ATTOR/VE Y Patented Sept. 12, 1950 UNITED STATES OFF ICE i I 2551,943 I CENTRIFUGAL CLUTCH UONTBJOL .Arnold Pitt, Toronto, Ontario, flanada,;assignor .to. Massey-Harris .011; rLtd., Toronto, Ontario,

"Canada, a corporation ofuflanada Application August "25, 19-15; Serial=No.-6-12,623

.The present invention relates to a starting clutch for devices such as cream separators, wherein the operating parts rotate at very high speed, the operating parts having considerable weight, thus possessing high initial inertia, so as torequire great initial power for starting.

"When a cream separator is electric motor driven, the motor must be much larger than is necessary to normally operate the separator in order to avoid possible injury to the motor or connecting parts. Otherwise the motor must operate at aconsiderable overload for the starting period and this endangers the motor,the brushes, .mo-tor connections and switches. In

either event there is necessarily a very high peak load during the starting period.

Thepresent invention provides means whereby the driving power required for first starting is practically zero and then'power is added to the motor gradually until the operating parts turn at 'f-ullspeed thus to avoid a dangerous peak load and the necessity for an unusually large-motor. The device is adapted to form a non slipping connection between the driving and driven members before full speed is reached.

In my device the driven member and separator rotor are first operated by a predetermined friction, the weight of the centrifugally operated clutch blocks on the driven element being such as will gradually increase the friction due to rotation of the driven element, the effect being to finally complete the engagement between the driving and driven elements a short time before the driven element reaches full speed. The arrangement and design of the centrifugal thrust is such as will increase the frictional contact to the driver in proportion to the square of the rotational speed of the driven member.

In my device the driver reaches a considerable speed before there is an appreciable load on the motor, therefore it protects the motor and gears from excessive starting strains, which might even be caused by a strong man who is in a hurry to get the device started. In other words a minimum size motor and minimum size transmission may be used with safety when my centrifugal clutch control is used.

To these and other useful ends my device consists of parts, combinations of parts or their equivalents and mode of operation as hereinafter described and claimed and shown in the accompanying drawings in which:

Fig. 1 is a longitudinal sectional view of my device and Fig. 2 is a transverse sectional view taken on line 2-2 of Figure 1.

2 i-Asmthus. illustrated the driven shaft of my centrifugal *clutchis, designated by reference:

character. l0 '-having secured thereto-a collar'll.

A collar 12 preferably rotatably rests on memberdt-andshaftlll has-an enlargement l3 which rests on collar 12. This enlargement for part of i'ts lengthis cut away" as at Hi -l4 as shown inthe-fi'gures. A hub i5 is at its" lower end'prefera-bly 'rotatably mounted on a collar l2 and restingorra-shoulder l6 as clearly illustrated in'Figchine'dsurface I B-"of member l5 and lie 'closeto surfaces M. Member I5 ispreferably provided" with aV be1t1'grooVe'2U;so this member may "bedriven by a beltfrom' a-motoror-otherwise.

- Generally shaft ['0 is operatively connected-to the separatorrotor unit'by means of a series of worm gears, this being necessary because the separator units may operate normally at an 8000 revolution per minute speed; therefore a considerable increase in speed is necessary between shaft I0 and the separator rotor.

An opening 25 is provided through the flattened portion of member I3 and apertures 26 are provided in members l8 which register with opening 25. I provide a light spring 21 which is positioned as shown in the figures and adapted to exert a very light pressure against members l8, so members I8 will lightly contact surface [9 when member [0 is at rest.

Thus it will be seen that when the motor or other power means which is operatively connected to member i5 is started, the only load to be carried by the motor is represented by the light friction between members l8 and I9 and between members ii and i2 and members l2 and I5. This friction however is enough to start rotation of the driven element.

It will be seen that the motor starts with practically no load and that it operates under a comparatively light load until shaft i0 is turned. at considerable speed and then as the speed of shaft I0 is increased the load will be increased at first slowly and then more and more rapidly, until member It! has at least reached more than one half normal speed. Clearly the action of the flat surfaces Hi will tend to urge members l8 outward as the power required is increased, thus to cooperate with centrifugal force to substantially 3 lock members l5 and l 8 together when maximum power and speed has been reached.

From the foregoing it will be seen that with applicants device a motor design to carry the normal load is sufficient as a driver and that all operating connections between the driver and separator rotor will not be subjected to high peak loads when starting. In other-words the motor and all its connecting parts including the separator transmission may be designed for the normal operating load of the separator or other de-- vice irrespective of inertia of the separator, rotor or other element driven by the clutch.

It will be understood that the separating e1e-- ment, the transmission element'and the transmission from shaft I!) to the separating element are mounted on ball bearings so that there is very little friction necessary between members and I8 to start the separator element to turning, these mountings being so near frictionless that applicants device will generally operate successfully without the use of spring 21 because of the friction between members H, and i2 and I 2 and i5.

Applicant's device is novel because the centrifugal clutch member is mounted on the driven shaft, the driving motor being connected to housing l5 which is at starting practically free to turn and that the clutch acts very gently at starting and increases its grip on the driving member as the speed is increased, that this increase c1utching effect acts on the basis of the square of the increase in speed of the driven member.

Having thus shown and described my invention I claim: Y

1. A self-serving automatic clutch of the character described comprising in combination, a driven shaft, a driving hubrotatably mounted on said driven shaft and means for driving the same, said driving hub having extended from one end thereof a circular drum, said driven shaft having secured thereon a circular projection, another projection integral with the first projection having flat surfaces on opposite sides thereof with a length substantially equivalent to the diameter of the first projection and a, thickness substantially equal to the diameter of the driven shaft, the length of said other projection being substantially one half the inside diameter of saiddrum, a pair of clutch blocks formed in the'shape of segments, their flat sides adapted to be in juxtaposition with the flat sides of said other projection and their curved surfaces adapted to permanently rest uniformly on the inside of said drum, apertures in said clutch blocks and a hole through said flattened extension and shaft registering with said clutch block apertures, a light push spring extending through the hole in said other projection and shaft and into said clutch block apertures.

2. A device as recited in claim 1 including, said drum having a cap secured to its outer end through which said driving shaft rotatably extends forming a closure for the drum. ARNOLD PITTQ REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 834,779 Wardwell Oct. 3, 1906 1,227,475 Matheeuwissen May 22, 1917 1,509,683 Miller Sept. 23, 1925 1,715,351 Bruckmann June 4, 1929 1,744,637 Jacobs et al Jan. 21, 1930 2,017,997 Thomas Oct. 22, 1935 2,373,462 Crow Apr. 10, 1945 FOREIGN PATENTS Number Country Date 17,293 Great Britain July 25, 1912 475,849 Great Britain Nov. 26, 1937 

